Gyrodial shows equality of apparent
Sun and true Earth rotations, proving by
both apparent gyroscope and real shadow
motions that these all are caused solely
by Earth's rotation: both spikes cast single
shadow by synchronization to Sun with
gyroscope below despite Earth's rotation.

This didactical toyis copyrighted.

It is 3D: click it with
mice to rotate and
roll the middle
button to zoom.